Gel electrolyte composition, photonic crystal electrochromic film and preparation method of photonic crystal electrochromic film

Abstract

The invention discloses a gel electrolyte composition, a photonic crystal electrochromic film and a preparation method of the photonic crystal electrochromic film. The gel electrolyte composition comprises the following components in percentage by mass: 60-90% of nano microspheres, 10-30% of a plasticizer, 0.1-1% of electrolyte salt and the balance of water. The gel electrolyte composition can be used for preparing a photonic crystal electrochromic film. Nanospheres are introduced into an electrolyte, then a gel electrolyte composition is compounded with an electrochromic layer and a transparent conductive film, a photonic crystal structure is constructed in the electrolyte layer through a bending induced oscillation shearing technology, a photonic crystal electrolyte layer is formed, and therefore the photonic crystal electrochromic film is obtained. The photonic crystal electrochromic film is provided with the gel electrolyte layer with the photonic crystal structure, more ion channels can be constructed, the photonic crystal electrochromic film is higher in response speed when being used in electrochromism, and multi-color change superposition is achieved through the photonic crystal electrochromic film and the electrochromic layer.

Description

Technical Field

[0001] The present invention belongs to the field of optical functional materials, and particularly relates to a gel electrolyte composition for preparing a photonic crystal electrochromic thin film, a photonic crystal electrochromic thin film, and a preparation method thereof. Background Art

[0002] Electrochromism refers to the phenomenon that electrochromic materials of a material undergo oxidation and reduction in a corresponding electrochemical reaction system, resulting in stable and reversible color changes in the optical properties (reflectivity, transmittance, absorbance, etc.) of the material, which appears as reversible changes in color and transparency in appearance. Electrochromic devices have great potential for use in decoration, display, smart windows, automotive anti-glare rearview mirrors, automotive sunroof dimming, building dimming, etc.

[0003] Traditional electrochromic thin films can be generally divided into two types from the structure: dye type and thin film type. The structure of the dye type electrochromic thin film is relatively simple, generally composed of a transparent conductive layer, an electrochromic layer, and a transparent conductive layer. The electrochromic layer contains small molecules such as dyes, viologens, and liquid crystals. The dye type electrochromic thin film changes color through principles such as electro-induced acid-base or electro-oxidation-reduction. However, since the electrochromic layers of the dye type electrochromic thin films are all small molecule types, the heat resistance and weather resistance of such thin films are relatively poor. The structure of the thin film type electrochromic thin film is a transparent conductive layer, an electrochromic layer, an electrolyte layer, an ion storage layer, and a transparent conductive layer. The electrochromic layer therein is generally a conductive polymer, Prussian blue, or a transition metal oxide, etc.

[0004] A photonic crystal is a type of optical material obtained by three-dimensionally and orderly arranging and crystallizing microspheres. The color display principle of a photonic crystal is that when light is incident on the photonic crystal, due to the periodic structure of the photonic crystal, the light undergoes diffraction or interference, thereby reflecting light of a specific wavelength, i.e., Bragg reflection. At present, prior art has disclosed processing nano-microspheres onto a thin film and making them orderly arrange and crystallize in three-dimensional space through a bending-induced oscillatory shear (ordering) technique to form a photonic crystal thin film, and industrialization has been achieved.

[0005] In the prior art, there is literature disclosing that introducing the structure of photonic crystals into electrochromic films can utilize the property of the photonic crystal structure to have total reflection for light in a specific wavelength band, obtaining a brand-new electrochromic film, improving the reflectivity of the electrochromic film and realizing the superposition of multi-color changes. For example, Chinese Patent Application CN202110325703.1 discloses an electrochromic photonic crystal film, its preparation method and application. In this technology, nano-microspheres are introduced into a polymer liquid crystal with electric field orientation, and a dye-type electrochromic film with a photonic crystal structure is obtained through bending-induced oscillatory shearing; Chinese Patent Application CN202110681551.9 discloses an electrochromic optical film and its preparation method. In this patent, nano-microspheres are introduced into a viologen solution with electrochromic properties, and a dye-type electrochromic film with a photonic crystal structure is obtained through bending-induced oscillatory shearing; Chinese Patent Application CN201210467926.2 discloses a preparation method of an electrochromic film with a photonic crystal structure. In this method, introducing a photonic crystal structure into a thin-film electrochromic film requires first constructing a photonic crystal template through capillary force, then electrochemically depositing an electrochromic layer on the template, and then washing away the template. This method is extremely cumbersome and difficult to be applied industrially.

[0006] Due to the high difficulty of introducing a photonic crystal structure into the electrolyte, structural color assembly process defects are required. So far, in thin-film electrochromic films, there has been no report on constructing a photonic crystal structure in the electrolyte layer. Summary of the Invention

[0007] To solve the drawbacks and deficiencies of the prior art, the primary object of the present invention is to provide a gel electrolyte composition for preparing a photonic crystal electrochromic film.

[0008] Another object of the present invention is to provide a preparation method of the above gel electrolyte composition for preparing a photonic crystal electrochromic film.

[0009] Another object of the present invention is to provide the application of the above gel electrolyte composition for preparing a photonic crystal electrochromic film in the preparation of a photonic crystal electrochromic film.

[0010] The present invention also provides a photonic crystal electrochromic film. In the photonic crystal electrochromic film, the gel electrolyte composition coated on the electrochromic film is regularized after film formation, and the nano-microspheres are arranged in a three-dimensional ordered manner to form a photonic crystal. The plasticizer and electrolyte salt are filled between the nano-microspheres, forming a photonic crystal electrolyte layer; the photonic crystal electrolyte layer forms a structural color through Bragg diffraction, and forms superposition or complementarity with the absorption color of the electrochromic layer.

[0011] The object of the present invention is achieved through the following technical solutions:

[0012] In the first aspect of the present invention, there is provided a gel electrolyte composition for preparing a photonic crystal electrochromic thin film. By mass percentage, its components include: 60-90% of nano-microspheres, 10-30% of a plasticizer, 0.1-1% of an electrolyte salt, and the balance of water.

[0013] More preferably, the components of the gel electrolyte composition for preparing a photonic crystal electrochromic thin film include: 70% of nano-microspheres, 20% of a plasticizer, 0.5% of an electrolyte salt, and the balance of water.

[0014] More preferably, the components of the gel electrolyte composition for preparing a photonic crystal electrochromic thin film include: 60% of nano-microspheres, 30% of a plasticizer, 1% of an electrolyte salt, and the balance of water.

[0015] More preferably, the components of the gel electrolyte composition for preparing a photonic crystal electrochromic thin film include: 89.9% of nano-microspheres, 10% of a plasticizer, 0.1% of an electrolyte salt, and the balance of water.

[0016] Preferably, the average particle size of the nano-microspheres is 100-400 nm, and the polydispersity index PDI is less than 0.15; the nano-microspheres are selected from at least one of polymer microspheres, inorganic microspheres, and polymer-inorganic composite microspheres.

[0017] More preferably, the polymer microspheres include at least one of polystyrene microspheres and core-shell structured polymer microspheres. The core material of the core-shell structured polymer microspheres includes organic or inorganic materials, and the shell material of the core-shell structured polymer microspheres includes polymer elastomer materials; the inorganic microspheres include at least one of silicon dioxide, titanium dioxide, iron tetroxide, and zinc sulfide.

[0018] Preferably, the plasticizer includes at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GLB), and diethyl carbonate (DEC).

[0019] Preferably, the electrolyte salt is a lithium salt.

[0020] More preferably, the lithium salt includes at least one of lithium perchlorate (LiClO4), lithium trifluoromethanesulfonate (LiTFSI), lithium tetrafluoroborate (LiBF4), and lithium hexafluorophosphate (LiPF6).

[0021] The preparation method of the above-mentioned gel electrolyte composition for preparing a photonic crystal electrochromic thin film includes the following steps: mixing the plasticizer and the electrolyte salt evenly to obtain a mixed solution, and then slowly dropping the mixed solution into the nano-microsphere emulsion under stirring to obtain the gel electrolyte composition.

[0022] Preferably, in the above preparation method, an auxiliary agent is further added to the nano-microsphere emulsion, such as one or more of a thickener, an antifoaming agent, a wetting agent, a leveling agent, a film-forming auxiliary agent, etc.

[0023] The gel electrolyte composition for preparing the photonic crystal electrochromic film can be used to prepare the photonic crystal electrochromic film.

[0024] In a second aspect of the present invention, a photonic crystal electrochromic film is provided, and its structure includes, in sequence: a transparent conductive film, an electrochromic film, a photonic crystal electrolyte film, and a transparent conductive film; wherein, the photonic crystal electrolyte film is prepared by coating the gel electrolyte composition for preparing the photonic crystal electrochromic film of the present invention into a film and then performing a regularization treatment, and the nano-microspheres in the photonic crystal electrolyte film are arranged in a three-dimensional order, and a plasticizer and an electrolyte salt are filled between the nano-microspheres.

[0025] Preferably, the thickness of the photonic crystal electrochromic film is 1-100 μm, the reflection wavelength is 350 nm-2500 nm, the blocking rate is 20%-30%, and the response speed is 2.4-4.8 s. In the range of the reflection wavelength of 350 nm-2500 nm, the photonic crystal electrolyte layer mainly reflects visible light and near-infrared light.

[0026] Preferably, the material of the electrochromic film can be one or a combination of two or more of polyaniline, polypyrrole, polythiophene and its derivatives, transition metal oxides, and hexacyano metal salts.

[0027] The preparation method of the photonic crystal electrochromic film of the present invention includes the following steps: First, an electrochromic film is prepared on the transparent conductive film of the substrate according to the conventional methods in the art (such as coating, vacuum evaporation method, cathode sputtering method, ion beam assisted deposition, chemical vapor deposition, sol-gel method, etc.); Then, the gel electrolyte composition for preparing the photonic crystal electrochromic film of the present invention is coated on the electrochromic film and the moisture is dried at a low temperature, and then a transparent conductive film is laminated on one side coated with the gel electrolyte composition; Finally, the obtained film is subjected to a regularization treatment to form a photonic crystal electrolyte film from the gel electrolyte composition, thereby obtaining the photonic crystal electrochromic film.

[0028] Preferably, the temperature of the low-temperature drying is 40-100 °C, and the time is 30 s-10 min; the coating amount of the gel electrolyte composition is limited by the thickness, and the thickness is 1-100 μm.

[0029] Preferably, the regularization treatment is carried out by bending-induced oscillatory shear technology, so that the nano-microspheres in the film are evenly distributed and regularly arranged, forming a three-dimensionally ordered structure.

[0030] The present invention also provides a photonic crystal electrochromic device, and its structure includes: substrate / transparent conductive thin film layer / electrochromic layer / photonic crystal electrolyte layer / transparent conductive thin film layer / substrate.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] 1. For the gel electrolyte composition of the present invention, by optimizing the types and dosages of nano-microspheres and plasticizers, the formed gel electrolyte layer has the function of preventing electrolyte leakage.

[0033] 2. At present, the method of constructing a photonic crystal structure in a thin-film electrochromic film is too cumbersome. In the present invention, nano-microspheres are introduced into the electrolyte, then the gel electrolyte composition is compounded with the electrochromic layer, and then a photonic crystal structure is constructed in the electrolyte layer through bending-induced oscillatory shear technology to form a photonic crystal electrolyte layer, thereby obtaining a photonic crystal electrochromic film. This method has a simple process and is easy to operate.

[0034] 3. For the photonic crystal electrochromic film of the present invention, the gel electrolyte layer with a photonic crystal structure therein can construct more ion channels, has a faster response speed in electrochromism, and realizes multi-color change superposition with the electrochromic layer. Description of the Drawings

[0035] Figure 1 It is a physical picture of the faded state of the photonic crystal electrochromic film prepared in Example 1;

[0036] Figure 2 It is a physical picture of the colored state of the photonic crystal electrochromic film prepared in Example 1;

[0037] Figure 3 It is the fading and coloring spectral curve of the photonic crystal electrochromic film prepared in Example 1;

[0038] Figure 4 It is the fading and coloring spectral curve of the photonic crystal electrochromic film of Comparative Example 1 dried at 100 °C;

[0039] Figure 5 It is the fading and coloring spectral curve of the electrochromic film of Comparative Example 1 without regularization treatment and without a photonic crystal structure. Detailed Description of the Invention

[0040] The present invention is described in more detail below:

[0041] The present invention provides a gel electrolyte composition and a photonic crystal electrochromic film prepared therefrom. Specifically, the gel electrolyte composition includes nano-microspheres, a plasticizer, and an electrolyte salt; the nano-microspheres may be 60 to 90 parts by weight, the plasticizer may be 10 to 30 parts by weight, and the electrolyte salt may be 0.1 to 1 part by weight.

[0042] The nano-microspheres form a photonic crystal after three-dimensional ordered arrangement and crystallization. When light enters the three-dimensional ordered arrangement structure of the nano-microspheres, diffraction or interference occurs, thereby reflecting light of a specific wavelength to obtain a structural color. Specifically, the nano-microspheres are selected from at least one of polymer microspheres, inorganic microspheres, and polymer-inorganic composite microspheres; the polymer microspheres include at least one of polystyrene microspheres and core-shell structure polymer microspheres, the core material of the core-shell structure polymer microspheres includes organic or inorganic materials, and the shell material of the core-shell structure polymer microspheres includes polymer elastomer materials; the inorganic microspheres include at least one of silicon dioxide, titanium dioxide, iron tetroxide, and zinc sulfide. The nano-microspheres are 60 to 90 parts by weight. In some preferred embodiments, specifically, they may be 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, etc.

[0043] In a more preferred embodiment, the nano-microspheres are core-shell structure polymer microspheres, the core material includes organic or inorganic materials, for example, it may be selected from more than one of polystyrene, silicon dioxide, iron tetroxide, polymethyl methacrylate, ethyl acrylate, indium tin oxide, arsenic trioxide, gold, and silver; the shell material includes polymer elastomer materials, for example, it may be selected from more than one of poly(butyl acrylate-methyl methacrylate) (P(MMA-BA)), poly(2-hydroxyethyl acrylate-2-hydroxyethyl methacrylate) (P(HEA-HEMA)) or poly(ethyl acrylate-methacrylic acid) (P(EA-MAA)), polydimethylsiloxane (PDMS), and polyurethane.

[0044] In some preferred embodiments, the average particle size of the nano-microspheres is 100-400 nm, and the polydispersity index PDI is less than 0.15. For example, the average particle size can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400 nm, etc. The nano-microspheres within the average particle size range described in the present invention can be used to prepare a photonic crystal film with a dazzling color effect. Moreover, after the nano-microspheres are compounded with an electrolyte salt and a plasticizer, a photonic crystal electrolyte layer with good ionic conductivity can be obtained. In the present invention, by selecting nano-microspheres with a polydispersity index PDI less than 0.15, the nano-microspheres can be evenly dispersed, making the structural color of the photonic crystal electrolyte layer more uniform.

[0045] The amount of the plasticizer is 10-30 parts by weight, preferably a low-volatility plasticizer, specifically including at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GLB), diethyl carbonate (DEC), etc. In some preferred embodiments, the amount of the plasticizer can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 parts by weight, etc. Introducing a photonic crystal structure into an electrolyte is of high difficulty, and it is necessary to consider the ionic conductivity and defects in the structural color assembly process. Therefore, simply compounding nano-microspheres with an electrolyte salt cannot successfully obtain a photonic crystal electrochromic film with a structural color and good ionic conductivity. In the present invention, by selecting the above types and amounts by weight of the plasticizer, the above defects are overcome. Moreover, when the nano-microspheres, plasticizer, and electrolyte salt in the amounts by weight described in the present invention are used together, a gel electrolyte layer can be formed, effectively preventing electrolyte leakage.

[0046] The electrolyte salt is a lithium salt, and the amount can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 part by weight, etc. In some preferred embodiments, the lithium salt includes at least one of lithium perchlorate (LiClO4), lithium trifluoromethanesulfonate (LiTFSI), lithium tetrafluoroborate (LiBF4), and lithium hexafluorophosphate (LiPF6). Within the range of 0.1-1 part by weight described in the present invention, adding the electrolyte salt can improve the response speed of the photonic crystal electrochromic film. However, if the added electrolyte salt exceeds 1 part by weight, the stability of emulsifying and dispersing the nano-microspheres in water will deteriorate, and even demulsification will occur.

[0047] In a second aspect of the present invention, there is provided a photonic crystal electrochromic thin film, the structure of which comprises, sequentially arranged: a transparent conductive thin film, an electrochromic thin film, a photonic crystal electrolyte thin film, and a transparent conductive thin film; wherein, the photonic crystal electrolyte thin film is prepared by coating a gel electrolyte composition for preparing the photonic crystal electrochromic thin film into a film and subjecting it to a regularization treatment, and the nano-microspheres in the photonic crystal electrolyte thin film are arranged in a three-dimensional ordered manner, and a plasticizer and an electrolyte salt are filled between the nano-microspheres. The gel electrolyte composition coated on the electrochromic thin film is subjected to a regularization treatment after film formation, and the nano-microspheres are arranged in a three-dimensional ordered manner to form a photonic crystal, and a plasticizer and an electrolyte salt are filled between the nano-microspheres to form a photonic crystal electrolyte layer; the photonic crystal electrolyte layer forms a structural color through Bragg diffraction and forms an overlay or complement with the absorption color of the electrochromic layer. The photonic crystal electrochromic thin film can be used in the fields of decoration, display, smart windows, automotive anti-glare rearview mirrors, automotive sunroof dimming, building dimming, etc.

[0048] In some preferred embodiments, the thickness of the photonic crystal electrochromic thin film is 1 to 100 μm, the reflection wavelength is 350 nm to 2500 nm, the blocking rate is 20% to 30%, and the response speed is 2.4 to 4.8 s. In the range of the reflection wavelength from 350 nm to 2500 nm, the photonic crystal electrolyte layer mainly reflects visible light and near-infrared light.

[0049] In some preferred embodiments, the material of the electrochromic thin film can be one or a combination of two or more of polyaniline, polypyrrole, polythiophene and its derivatives, transition metal oxides, and hexacyano metal salts.

[0050] In some preferred embodiments, the transparent conductive thin film refers to a transparent conductive layer formed by coating or plating a transparent conductive material on a plastic substrate, the thickness of the transparent conductive layer is 50 to 500 nm, the sheet resistance is 1 to 500 ohms, and the type, thickness, and sheet resistance of the transparent conductive material are not limited and can be appropriately selected according to the purpose. The transparent conductive material includes, but is not limited to, inorganic materials such as indium tin oxide (ITO) doped with tin, gallium zinc oxide doped with titanium (GZO), antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), transparent carbon nanotubes, silver nanowires, gold nanowires, platinum nanowires, and copper nanowires, or a combination of two or more of them.

[0051] In some preferred embodiments, the regularization treatment is carried out by a bending-induced oscillatory shear technique to make the nano-microspheres in the thin film evenly distributed and regularly arranged to form a three-dimensional ordered structure.

[0052] The described photonic crystal electrochromic thin film is prepared by the following steps: First, an electrochromic thin film is prepared on the transparent conductive thin film of the substrate according to conventional methods in the art (such as coating, vacuum evaporation method, cathode sputtering method, ion beam assisted deposition, chemical vapor deposition, sol-gel method, etc.); Then, the gel electrolyte composition for preparing the photonic crystal electrochromic thin film of the present invention is coated on the electrochromic thin film and the moisture is dried at a low temperature, and then a transparent conductive thin film is laminated on one side coated with the gel electrolyte composition; Finally, the obtained thin film is regularized to form a photonic crystal electrolyte thin film from the gel electrolyte composition, thereby obtaining the photonic crystal electrochromic thin film.

[0053] In some preferred embodiments, the temperature for low-temperature drying is 40-100 °C and the time is 30 s-10 min; the coating amount of the gel electrolyte composition is defined by thickness, and the thickness is 1-100 μm.

[0054] Based on the above invention content, the present invention also provides a photonic crystal electrochromic device, and its structure includes: substrate / transparent conductive thin film layer / electrochromic layer / photonic crystal electrolyte layer / transparent conductive thin film layer.

[0055] The present invention will be further described in detail below in conjunction with examples and drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be directly purchased from the market. For process parameters not specifically noted, conventional techniques can be referred to.

[0056] Preparation of nano-microsphere emulsion

[0057] Preparation Example 1: An emulsion of PS@P(MMA-BA) nano-microspheres (polystyrene@poly(butyl acrylate-methyl methacrylate) nano-microspheres) was prepared according to the method described in Chinese Patent Application CN110804127B, and the core particle size was controlled to be 200 nm and the total particle size was 250 nm to obtain the emulsion of Preparation Example 1.

[0058] Preparation Example 2: An emulsion of PS@P(MMA-BA) nano-microspheres was prepared according to the method described in Chinese Patent Application CN110804127B, and the core particle size was controlled to be 200 nm and the total particle size was 270 nm to obtain the emulsion of Preparation Example 2.

[0059] Example 1

[0060] This example provides a preparation method of a photonic crystal electrochromic thin film, including the following steps:

[0061] Step ①: Preparation of the gel electrolyte composition: 0.5 g of lithium hexafluorophosphate was added to 20 g of propylene carbonate and dissolved thoroughly. Then, under stirring, it was slowly added dropwise to an emulsion containing 70 g of PS@P(MMA-BA) nanospheres (the emulsion of Preparation Example 1) and stirred evenly to obtain the gel electrolyte composition; the sum of the masses of lithium hexafluorophosphate, propylene carbonate, the PS@P(MMA-BA) nanospheres in the emulsion of Preparation Example 1, and the water in the emulsion of Preparation Example 1 was 100 g;

[0062] Step ②: A layer of PEDOT:PSS was coated on the ITO film using a 30-μm doctor blade and dried and cured to form an electrochromic layer with a thickness of 0.2 - 50 μm;

[0063] Step ③: The gel electrolyte composition was coated on the above-mentioned electrochromic layer using a 30-μm doctor blade, dried at 60 °C for 1 min to remove the moisture, and another ITO film was laminated to obtain an electrochromic film;

[0064] Step ④: The electrochromic film was regularized to form a photonic crystal electrolyte layer with a thickness of 15 μm, thereby obtaining a photonic crystal electrochromic film.

[0065] The components of Examples 2 to 11 and Comparative Example 1 are specifically shown in Table 1. Except for the types and amounts of raw materials, the preparation methods of Examples 2 to 11 and Comparative Example 1 are the same as those of Example 1 and will not be elaborated here.

[0066] Example 11: Referring to the method of Example 1, the emulsion of Preparation Example 1 was replaced with the emulsion of Preparation Example 2, and the rest remained unchanged.

[0067] Comparative Example 1: No regularization treatment was carried out

[0068] Step ①: Preparation of the gel electrolyte composition: 0.5 g of lithium hexafluorophosphate was added to 20 g of propylene carbonate and dissolved thoroughly. Then, under stirring, it was slowly added dropwise to an emulsion containing 70 g of PS@P(MMA-BA) nanospheres (the emulsion of Preparation Example 1) and stirred evenly to obtain the gel electrolyte composition; the sum of the masses of lithium hexafluorophosphate, propylene carbonate, the PS@P(MMA-BA) nanospheres in the emulsion of Preparation Example 1, and the water in the emulsion of Preparation Example 1 was 100 g;

[0069] Step ②: A layer of PEDOT:PSS was coated on the ITO film using a 30-μm doctor blade and dried and cured to form an electrochromic layer;

[0070] Step ③: The gel electrolyte composition was coated on the above-mentioned electrochromic layer using a 30-μm doctor blade, dried at 60 °C for 1 min to form a 15-μm electrolyte layer, and another ITO film was laminated to obtain an electrochromic film.

[0071] Performance Test:

[0072] 1. Reflection Wavelength and Blocking Rate

[0073] The spectral data corresponding to the electrochromic films prepared in the above examples and comparative examples were measured using a V-5600PC visible spectrophotometer (purchased from Shanghai Yuanxi Instruments Co., Ltd.) at angles of 90°, 75°, 60°, 45°, and 30° for the samples respectively, and the reflection wavelength and blocking rate were obtained.

[0074] 2. Response Time

[0075] The electrochromic films prepared in the above examples and comparative examples were respectively subjected to a fading performance test using a DC power supply at a driving voltage of 3V, and the time when the color of the device was observed to change significantly with the naked eye was recorded as the response time.

[0076] Table 1

[0077]

[0078]

[0079] In Example 10*, the water content in the gel electrolyte composition was 0. During the preparation process, the nano-microsphere emulsion needed to be centrifuged and freeze-dried first, and then nano-microspheres without water were obtained.

[0080] Figure 1 This is a physical picture of the fading state of the photonic crystal electrochromic film prepared in Example 1. It can be seen that on a black background, it is mainly the red structural color of the photonic crystal electrolyte layer, and on a white background, it is the superposition of the gray absorption color of the electrochromic layer and the red structural formula. Figure 2 This is a physical picture of the colored state of the photonic crystal electrochromic film prepared in Example 1. It can be seen from the figure that in the colored state, the electrochromic layer changes from gray to blue, the red structural color of the photonic crystal electrolyte layer becomes significantly weaker on a black background, and it is basically the gray absorption color on a white background.

[0081] The characteristic of the photonic crystal structural color is the reflection peak of the spectrum. Figure 3 This is the fading and coloring spectral curve of the photonic crystal electrochromic film prepared in Example 1. From Figure 3 it can be seen that the reflection peak is very sharp, indicating that the arrangement and assembly of the photonic crystal microspheres are very good. Figure 4 This is the fading and coloring spectral curve of the photonic crystal electrochromic film of Comparative Example 1 dried at 100°C. It can be seen from the figure that Figure 4 the reflection peak is weaker, representing that the arrangement and assembly of the photonic crystal microspheres are poor. Figure 5 This is the fading and coloring spectral curve of the electrochromic film prepared in Comparative Example 1. Figure 5No reflection peak of the photonic crystal structure can be seen, because after the electrochromic thin film was prepared in Comparative Example 1, no regularization treatment was carried out, and the nanospheres failed to form a three-dimensionally ordered structure.

[0082] From Table 1 and the appendix Figures 1 to 5 It can be seen that the photonic crystal electrochromic thin film provided by the embodiments within the scope of the present invention has a faster response speed in electrochromism and realizes multi-color change superposition with the electrochromic layer.

[0083] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A gel electrolyte composition for preparing a photonic crystal electrochromic thin film, characterized in that, By mass percentage, the components of the gel electrolyte composition include: 60-90% of nano-microspheres, 10-30% of plasticizer, 0.1-1% of electrolyte salt, and the balance of water.

2. The gel electrolyte composition for preparing a photonic crystal electrochromic thin film according to claim 1, wherein The average particle size of the nano-microspheres is 100-400 nm, and the polydispersity index PDI is less than 0.15; the nano-microspheres are selected from at least one of polymer microspheres, inorganic microspheres, and polymer-inorganic composite microspheres.

3. The gel electrolyte composition for preparing a photonic crystal electrochromic thin film according to claim 2, characterized in that, The polymer microspheres include at least one of polystyrene microspheres and core-shell structure polymer microspheres; the core material of the core-shell structure polymer microspheres includes organic or inorganic materials, and the shell material of the core-shell structure polymer microspheres includes polymer elastomer materials; the inorganic microspheres include at least one of silicon dioxide, titanium dioxide, iron tetroxide, and zinc sulfide.

4. The gel electrolyte composition for preparing a photonic crystal electrochromic thin film according to claim 1, wherein The plasticizer includes at least one of ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and diethyl carbonate; and / or, the electrolyte salt includes at least one of lithium perchlorate, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, and lithium hexafluorophosphate.

5. A photonic crystal electrochromic thin film, characterized in that, Its structure includes, in sequence: a transparent conductive film, an electrochromic film, a photonic crystal electrolyte film, and a transparent conductive film; wherein, the photonic crystal electrolyte film is prepared by coating and forming the gel electrolyte composition for preparing the photonic crystal electrochromic film according to any one of claims 1-4 and then performing a regularization treatment, and the nano-microspheres in the photonic crystal electrolyte film are arranged in a three-dimensional order, and the plasticizer and the electrolyte salt are filled between the nano-microspheres.

6. The photonic crystal electrochromic thin film according to claim 5, wherein The thickness of the photonic crystal electrochromic film is 1-100 μm, the reflection wavelength is 350 nm-2500 nm, the blocking rate is 20%-30%, and the response speed is 2.4-4.8 s.

7. The photonic crystal electrochromic thin film according to claim 5, characterized in that, The material of the electrochromic film is one or a combination of two or more of polyaniline, polypyrrole, polythiophene and its derivatives, transition metal oxides, and hexacyano metalates; and / or, the material of the transparent conductive film includes one or a combination of two or more of indium tin oxide doped with tin, zinc gallium oxide doped with titanium, antimony-doped tin oxide, fluorine-doped tin oxide, transparent carbon nanotubes, silver nanowires, gold nanowires, platinum nanowires, and copper nanowires; and / or, the thickness of the transparent conductive film is 50-500 nm, and the sheet resistance is 1-500 ohms.

8. The method for preparing the photonic crystal electrochromic thin film according to any one of claims 5 to 7, characterized in that, It includes the following steps: First, an electrochromic film is prepared on the transparent conductive film of the substrate; then, the gel electrolyte composition for preparing the photonic crystal electrochromic film according to any one of claims 1-4 is coated on the electrochromic film and the moisture is dried at a low temperature, and then a transparent conductive film is laminated on one side coated with the gel electrolyte composition; finally, the obtained film is subjected to a regularization treatment to form a photonic crystal electrolyte film from the gel electrolyte composition, thereby obtaining the photonic crystal electrochromic film.

9. The preparation method according to claim 8, characterized in that, The temperature of the low-temperature drying is 40-100 °C, and the time is 30 s-10 min; the coating amount of the gel electrolyte composition is limited by the thickness, and the thickness is 1-100 μm.

10. The preparation method according to claim 8, characterized in that, The regularization process is carried out by means of the bending-induced oscillatory shearing technique, so that the nano microspheres in the film are evenly distributed and regularly arranged, forming a three-dimensionally ordered structure.

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